1. Field of the Invention
The present invention relates to an illumination device to be used as a surface light source having uniform brightness; for example, as backlight for a liquid crystal display.
2. Prior Art
A typical LCD device includes a liquid crystal display panel, and a backlight system mounted under the liquid crystal display panel for supplying light beams thereto. The backlight system is generally into one of two types—an upright type or an edge-light type—according to the position in which a lamp is installed in a backlight unit of the backlight system.
In the case of an upright type backlight system, the lamp is installed at a rear portion of the liquid crystal display panel. A light spreading plate and a light reflection plate are installed at front and rear portions of the lamp respectively, so that light beams are directly output onto a liquid crystal display panel.
Referring to FIG. 6, U.S. Pat. No. 6,330,150 issued to Samsung Electronics Co., Ltd. on Dec. 11, 2001 discloses a liquid crystal display module 100 using an upright type backlight system. The liquid crystal display module 100 includes a liquid crystal display panel 110 having a plurality of lamps 130 engaged therein. The liquid crystal display panel 110 is mounted in a panel bracket 120.
The bracket 120 is used to secure a frame of the liquid crystal display panel 110, and the lamp 130 is exchanged by opening and closing a cover (not labeled) of the bracket 120.
The liquid crystal display panel 110 includes an upper surface 111, in which a plurality of rectangular holes 112 is defined. Each lamp 130 is engaged in a corresponding rectangular hole 112.
Each lamp 130 includes a hexagonal head portion (not labeled), a luminous body (not labeled) extending from the head portion, and a rubber plate 131 attached on a lateral surface of the head portion. The rubber plate 131 has a predetermined elasticity. When the lamp 130 is inserted into the rectangular hole 112 of the liquid crystal display panel 70, the rubber plate 131 is elastically compressed and received in the hole 112. Once the lamp 130 has been completely inserted into the hole 112, pressure on the rubber plate 131 is released. The rubber plate 131 expands so that it is resiliently engaged in the hole 112. The lamp 130 is thus fixed at the hole 112 and secured in the liquid crystal display panel 110.
When exchanging the lamp 130, the rubber plate 131 attached at the head portion is compressed and released from the hole 112. The lamp 130 is then slid out from the liquid crystal panel 110.
However, the liquid crystal display module 100 has certain disadvantages. First, each lamp 130 is engaged in a corresponding rectangular hole 112 of the liquid crystal display panel 110. During engagement and removal of the lamp 130, the lamp 130 is liable to abrade an edge of the liquid crystal display panel 110 at the hole 112 and thereby sustain damage. Second, only one rubber plate 131 is used to fix each lamp 130 in the liquid crystal panel 110. This engagement may not be secure, particularly if the LCD module 100 is subjected to vibration or shock during use or transportation.
Therefore, it is desirable to provide a backlight system which overcomes the above-described disadvantages of conventional backlight systems.